I read that Easter is always the 1st Sunday after the 1st full moon after the Spring Equinox (which is March 20). This dating of Easter is based on the lunar calendar that Hebrew people used to identify passover, which is why it moves around on our Roman calendar. Is this correct?
The person who wrote this is wrong about the dating of Easter in the western church. It is connected to the Spring Equinox but is not related to Passover. (Many Eastern Orthodox churches still connect the dating of Easter to Passover.)
For the west, Easter replaced the pagan Feast of Ishtar, a fertility goddess, which occurred at the time of the Spring Equinox. That’s how Easter got its name and why colored eggs and rabbits, symbols of fertility, came to be part of it. Some of the pagan rituals most abhorrent to God were part of the Feast of Ishtar.
When Christianity became the official religion of the Roman Empire they simply replaced the pagan festival with a Christian one, keeping many of the pagan rituals. (The Romans did the same thing with Christmas which had been the Feast of Saturnalia.)
Passover occurs 14 days after the first day of Nisan, the first month on the Jewish calendar (Lev. 23:5). Months are based on phases of the moon, each month beginning with the so called crescent moon.
The Feast of First Fruits comes on the day after the Sabbath after Passover (Lev. 23:11) which means it’s always a Sunday since their sabbath is Saturday. In the year Jesus was crucified the Feast of First Fruits was three days after Passover and became known as Resurrection Morning in the early church.